强流带电粒子束的传输矩阵理论

近年来,强流带电粒子束在国民经济许多部门获得了广泛的应用。为了设计强流粒子加速器及其它强流带电粒子束装置,必须进行强流带电粒子光学的计算。从物理学的角度看来,强流带电粒子束运动的问题在电动力学中己经解决,通过解粒子运动方程和电位的Poisson方程即可求出带电粒子束中各粒子的运动状况。但是这一方法过分繁杂,而且我们关心的并不     

四极磁场中粒子束输运的非线性分析及模拟

为了提高粒子在四极磁场中输运轨迹计算的精度,基于李代数方法,分析和计算粒子束在四极磁场中空间电荷的非线性效应,得到二级近似下粒子坐标的映射公式,编写了粒子束在四极磁场中传输的模拟程序QML。用模拟程序对四极磁场中的传输进行了模拟计算,并对模拟结果进行了分析。模拟结果表明,在空间电荷的非线性效应的影响下相图产生了明显的扭曲,对粒子束包络曲线横向发散作用明显。     

电子直线加速器中计入纵向与横向耦合效应的束流包络线方程组

一、引言从束流动力学的观点出发,对于粒子束在直线加速器中的运动,有两种主要的分析方法,也即粒子轨迹跟踪法及考察束流包络运动的方法。前者是通过解单粒子运动方程,跟踪大量的单粒子运动轨迹而后进行分析;后者则是通过解束流的包络线方程,根据束流包络的变化来进     

径向电场中带电粒子束的质量分离

带电粒子束已广泛应用于科学、工程和国民经济的诸多领域,而质量色散及分离是电磁质量分离器和谱仪等领域中的关键科学问题。本文推导离子束流在径向电场中的运动轨迹解析表达式,应用MATLAB模拟特征质量离子的聚焦轨迹。从轨迹图中可看出,不同质量离子在径向电场中按质量聚焦,具有明显的分离效果。本文的研究结果为等离子体光学质量分离装置的研制奠定了理论基础,同时对于特殊位形电磁场控制带电粒子束等相关领域的研究具有一定的借鉴意义。     

Calutron源引出电极

一、前言在所有产生带电粒子束的系统中,为了得到聚焦良好的带电粒子束,引出电极的几何形状、几何参数等几何条件,对于带电粒子束的品质是很重要的。在利用电磁法达到同位素分离目的的同位素电磁分离器     

粒子束中性化方案研究

强流带电粒子束的中性化效率是关系到中性粒子束武器能否可行的一个关键,本年度重点研究了H-粒子束的中性化方案。 H-粒子束的中性化方案主要有薄膜中性化方案与气室中性化方案2种。薄膜中性化方案具有结构简单、不破坏加速器束流线上的真空度、能有效降低中性粒子束武器的尺寸     

全国荷电粒子源粒子束学术交流会论文选编

前　　言“2 0 0 1全国荷电粒子源粒子束学术交流会”于 2 0 0 1年 11月 2 6日至 12月 1日在深圳 -海口举行。这是第三次由中国电工技术学会电子束离子束专业委员会、粒子加速器学会离子源专业组、中国电子学会电子束焊接专业委员会和北京电机工程学会加速器专业委员会联合主办的我国荷电粒子源和粒子束的物理、技术、装置与应用领域的多学科交叉综合性学术交流会。前两次是于 1997年和 1999年分别在湖南索溪峪和四川成都举行。荷电粒子源包括离子源和电子源 ,早期曾在粒子加速器、同位素分离器等核子仪器和实验方法研究的推动下得到了迅速…     

减小直线加速器耦合腔中不对称性的方法

随着高能物理的发展,特别是大型对撞机、FEL和高亮度同步辐射光源,均对直线加速器的性能提出了更高的要求。单边耦合器结构的不对称性破坏了耦合腔中场的对称性分布,降低了束流的品质。为了改善不对称性,利用CST微波工作室模拟设计了X波段偏心耦合器、双对称耦合器以及介质棒加载耦合器,并对腔中场分布的均匀性进行了分析,而且进行了粒子跟踪。计算结果表明采用新方法设计的加载介质棒耦合器耦合腔中场分布的对称性较好。粒子束团通过该种耦合器和一段加速结构后,束团的分布几乎完全处在束流孔中心,而且束流能散有明显改善。     

微传输矩阵及其在强流带电粒子束光学计算中的应用

本文提出了微传输矩阵的概念,讨论了它的基本性质,并将它应用于强流带电粒子束的光学计算。     

单粒子微束品质优化装置研制的设想

对影响单粒子微束装置束品质的因素进行了全面分析，并提出了一种优化单粒子微束装置束品质的方法——用束流发射度精确测量与粒子束聚焦自动调节装置改进单粒子微束装置瞄准器出口束斑。     

均匀二极磁场的李代数分析

用要代数方法分析了带电粒子在二级磁场中的传输及其像差问题。     

Design criteria for an angle resolved electron spectrometer of novel toroidal geometry

A charged particle analyser based on the use of polar trajectories in a toroidal sector is described in which a large number of particle emission angles are detected simultaneously. An analysis of the trajectories of particles in this class of analyser is presented and we develop transfer matrices which enable the imaging properties of such devices to be determined analytically. Expressions for the axial and radial magnification and for the energy resolving power are also derived. The analysis and the derived properties are compared with a numerical simulation and with all available published data.     

二极磁铁的三级Lie映射

用Ｌｉｅ代数方法分析了带电粒子在二极磁铁中的运动，得到在六维相空间中相对论凿子的三级近似轨迹。     

Charge state of low energy reflected particles

Low energetic noble gas particles, scattered from a metal surface, have only a small probability to leave this surface in the charged state. Even particles scattered from target atoms in the outermost surface layer are nearly all neutralised. Consequently analysis of the charged fraction of the scattered beam guarantees that information is obtained of only this layer. To quantify these low energy ion scattering (LEIS) measurements data on the ion fractions must be known, especially because these fractions have such small values. Besides this practical aspect there is the fundamental question: how does it work, this neutralization mechanism, does the transition rate for electron capture of the scattered particle depend upon its distance from the surface, or are it distant binary collisions with individual metal atoms along its trajectory which give rise to interatomic Auger transitions.Already for many years Hagstrum's theory has been applied to correct for the neutralization effect. This theory is developed to study the ejection of Auger electrons as a result of the interaction of low energetic noble gas ions with a metal surface. Due to the low ion energies used in those experiments, namely the tens eV-region, Hagstrum assumed a structureless metal surface. This means that the normal velocity of the scattered particle, v₁, takes part in determining the ion fraction and not v, the velocity of the scattered particle in its trajectory. It is a question, however, whether this theory may be applied for keV-ions. The distance between scattered particle and metal surface is for these energies namely much smaller than for tens eV's and the surface can no longer be regarded as a plane; this may result in dominating interatomic Auger transitions. But then the trajectory of the scattered particle with its velocity v plays a part in determining the occurrence of neutralization.Another mechanism that may determine the charge state of the scattered particle occurs in the violent collision; neutralization as well as (re)ionization of this particle may take place and influence its charge state. These models are treated in this review and discussed with the help of recent measurements and results of computer simulations of reflected particles.     

Screener3D:a gaseous time projection chamber for ultra-low radioactive material screening

In experiments searching for rare signals,back-ground events from the detector itself are some of the major factors limiting search sensitivity.Screening for ultra-low radioactive detector materials is becoming ever more essential.We propose to develop a gaseous time projection chamber(TPC)with a Micromegas readout for radio screening.The TPC records three-dimensional tra-jectories of charged particles emitted from a flat sample placed in the active volume of the detector.The detector can distinguish the origin of an event and identify the particle types with information from trajectories,which significantly increases the screening sensitivity.For a particles from the sample surface,we observe that our proposed detector can reach a sensitivity higher than 100 p Bq m-2 within two days.     

Computer investigation of ion beam optics for a Freeman type ion source system

The present work investigates the computer analysis of the ion beam properties produced by a Freeman type system. The extraction for such system is composed of four electrodes that permit to keep a fixed output energy by means of two accelerating gaps and one decelerating gap. The latter allows reducing the beam divergence angle. The combination of the acceleration/deceleration sections provides to keep a low beam emittance at the source outlet. The simulation of single charged argon ion trajectories for a plasma concave of curvature 4 mm was first studied with and without space charge effect using acceleration/deceleration extraction system with the aid of the SIMION computer program. The voltage applied to the accelerating electrode was optimized to accomplish the suitable ion trajectories without hitting the extraction electrode. Then, two additional studies were performed: the influence of the acceleration voltage and extraction voltage on the beam emittance and beam diameter; and the effect of the extraction gap width (distance between the plasma emission surface and the acceleration electrode) on the shape of the ion beam envelope and the position of the ion beam waist. Last, the influence of the space charge on the ion beam envelope was also investigated.     

Ion microscopy using magnifying ion TRANSPORT systems and position sensitive detectors

Microanalysis by detection of charged particles may be speeded up by several orders of magnitude when position sensitive detectors are used at the focus of a magnifying lens system. Using beam optics calculations a resolution on the sample of 40 × 7 μm² appears possible with available quadrupoles with an acceptance of 0.375 msr selecting particle energy within a 1.2% range. Even submicron resolution may be possible when energy is selected within a 0.3% range. The projection system has an appreciable field of view: sample regions of the order of 1 mm² may be studied simultaneously when appropriate detectors are used.     

激光烧蚀铀材料生成铀微粒的形态学研究

本文以激光器作光源,利用激光的高温烧蚀特性,以激光束烧蚀金属铀和二氧化铀材料,模拟高温条件下形成铀微粒的过程,用扫描电子显微镜和透射电子显微镜对铀材料及产生的含铀微粒的形态学特点进行了表征。实验表明,在激光束的轰击下,两种靶材料均出现熔化现象,铀金属表面呈现明显波纹状结构,二氧化铀的表面轰击边缘处呈现趋球状物堆积。生成的铀氧化物微粒为μm级形态不规则微粒及1 μm左右的球形微粒,说明铀在高温过程中产生球形微粒。对比研究了来自高温爆炸过程的金属银微粒,进一步验证了高温高压过程会产生球形微粒。结果表明,密实的铀氧化物微球是铀材料参与高温化学过程的结果,与低温过程中的剥蚀作用有明显的差别,是高温化学过程的特征,这为高温高压环境中的微粒分析提供了参考依据。     

Submicron position-sensitive detector

A method has been developed to measure precisely the coordinates of charged particles incident between adjacent strips of a strip detector. The position sensitivity of an inter-strip gap has been studied by means of a pulsed laser beam and irradiation by -particles of a ²²⁶Ra-source. The capacitive division of charge generated by the incident particle depends on the position of its track. Its coordinates were determined by two-dimensional amplitude analysis of the charges collected by neighbouring strips. This method of coordinate determination applied to studies of spatial and energy distributions of electromagnetic as well as charged particle beams (including radioactive ion beams) of low intensity could provide the highest level of the precision limited by the track dimensions of charged particles, i.e. percents of a micrometer.